An instrument used to count the frequency of recurrent electronic events and display the count on the panel of the instrument in numeric form. May also include facilities for a readout printed on tape. May include facilities for a very accurate output which can be used as a secondary transfer standard. It can be used to measure frequency, period, time interval, phase angle, frequency ratio, and for multiple period averaging. See also COUNTER, ELECTRONIC, DIGITAL and INDICATOR, DIGITAL DISPLAY.